1. Field of the Invention
The present invention relates to swimming pool pop-up fittings, and particularly to pop-up fittings that incorporate indexing or camming means adapted to positively, incrementally rotate the pop-up head of the fitting during projection and retraction of the head.
2. Description of the Prior Art
One of the more effective camming mechanisms for pop-up heads in a swimming pool cleaning system is disclosed in U.S. Pat. No. 3,408,006, issued to Stanwood on Oct. 29, 1968 for "Liquid Jet Producing Device".
The Stanwood device includes a cylindrical housing designed to be threaded onto the exterior surface of a water inlet pipe, the housing and pipe both eventually being embedded in the concrete of the associated pool wall.
A cylindrical stationary structure which includes camming surfaces is attached to the inside of the housing. The pop-up head of the device is fitted within the stationary structure and includes a nozzle and an attached stem which carries a transverse camming pin. The pin rides upon the camming surfaces to incrementally rotate the nozzle as the head moves between its projected and retracted positions under the influence of water cycled through the inlet pipe. When water flows to the head it pops up. When the water flow is stopped, a bias means in the form of a spring pulls the head down.
Water pressure in the upper position of the head is effective to hold or constrain the head against rotation. Typically the water flow is maintained long enough for the water stream or jet issuing from the nozzle to extend a considerable distance from the head to thereby cover a fairly large surface of the pool during successive cycles of projection and retraction of the head.
It is desirable that the length and outer diameter of the head be minimized to reduce its overall size. Otherwise, the cavity that must be formed in the concrete around the inlet pipe to receive the head and gain access to the inlet pipe becomes too large, perhaps so large as to affect the structural integrity of the pool wall. Of course, a bulky or large head is also more expensive to make, stock and transport.
In Stanwood the wall which carries the camming surfaces surrounds the stem of the head. This presents some problems. If the wall is made large and thick enough to enable the formation of generous size camming surfaces that are deep enough to properly engage and guide the camming pin, the head structure around the stem becomes larger or bulkier. On the other hand, if the wall is made relatively small in diameter, the resultant camming surfaces can become too small to be sensitively responsive to the action of the stem camming pin. Stated another way, if the amount of travel of a camming pin over camming surfaces during stem reciprocation is relatively short, it becomes difficult to impart precise, repetitive incremental rotations to the stem.
Small cams also tend to be delicate, and subject to premature wear and operational failure, and to clogging by dirt and grit in the water.
The camming pin of Stanwood also undesirably extends across the flow path of water through the stem. This arrangement of the pin provides structural integrity for the pin. If the pin were to be made in two parts extending from opposite sides of the stem, there would be no obstruction to the flow of water, but structural integrity would require that the thickness of the stem wall be increased. As previously indicated, this would undesirably increase the diameter of the stem, and therefore the overall size of the pop-up fitting, or it would reduce the inner diameter of the stem and this would reduce the water flow through the head.
U.S. Pat. No. 4,322,860, issued to Gould on Apr. 6, 1982 for "Pool Cleaning Head With Rotary Pop-up Jet Producing Element" discloses a camming means similar to that of Stanwood in that the camming means is located in the stem area of the pop-up head.
It is an object of the present invention to provide a pop-up head design particularly suited for use in systems such as that disclosed in my copending patent application Ser. No. 07/428,862, filed Oct. 30, 1989 and entitled "Method and Apparatus for Removing Sediment From a Pool". In that system a combination of rotatable and non-rotatable pop-up fittings are mounted flush with the walls or inner surfaces of a swimming pool. They are acted upon by water pressure to direct jets of water over adjacent surfaces of the pool to scrub or cleanse sediment and debris from such areas and urge it toward the main drain or other collection point for ultimate separation from the pool water.
As discussed in more detail in the application, the pop-up head of each of the rotatable or rotary fittings issues a stream of water which changes in angular direction with each successive actuation of the head. The stream sweeps a circular sector in the vicinity of the head and develops an area of local turbulence. The head of the fixed fitting does not rotate, instead producing a long duration or continuous stream of water which acts in a predetermined direction to establish a water "highway". This continuous stream picks up sediment suspended in the local areas of turbulence which are produced by the rotary heads. The sediment is thus urged toward a collection point such as the main drain.
In their projected positions, the heads of both the rotary and fixed fittings are constrained against rotation. As a result, the jet stream which each produces is relatively straight and of long duration so that its influence extends a greater distance than would be the case if the heads rotated.
To avoid using large pumps, or a multiplicity of pumps, the system of my copending application preferably includes a valving arrangement which is cyclically operated to apply the output of a main pump sequentially to the various rotary heads. It is optional to use the output of a second or booster pump to constantly apply water under pressure to the fixed heads to develop the longer duration water "highways" mentioned above.
Since both rotary and fixed heads are used in such a system, economies can be realized by using a pop-up fixture which can be quickly converted to serve as either a fixed head or a rotary head. Neither Stanwood nor Gould discloses such a convertible structure.
Similarly, economies can be achieved by providing a head whose output is adjustable. Thus, large capacity heads could be used to sweep relatively large, uninterrupted pool surfaces, whereas lesser capacity heads could be employed for smaller areas that require specific targeting, such as pool steps, benches, corners and spa steps. At present the capacity of a head can be changed by drilling out different sizes of nozzle opening, by providing different sizes of knock out openings in the head, by driving different orifice size nozzle plugs into a standard size nozzle opening, or by various similar means. However, none of these measures is entirely satisfactory because they are not capable of being done quickly, and they only provide a one-time adjustment which does not allow for convenient further changes in water flow rate. Moreover, the configuration of prior art heads often does not provide a relatively long nozzle, which is desirable to produce an efficient jet stream.
It is preferred by swimming pool installers to slip fit the lower end of the pop-up head housing into the open end of the water inlet pipe from which it receives its water. Among other advantages, the connection can be easily and quickly made using a slip fit glue joint, rather than a threaded connection. Further, a threaded joint requires that fresh concrete be cleared away from the inlet pipe down past the threaded end portion and of course the threaded portion would have to be cleaned of all concrete in readiness for later attachment of the pop-up head.